1. Field of the Invention
The present invention relates to a joint structure of a pipe.
2. Description of the Related Art
FIG. 7 is a perspective view showing a conventional joint structure of a pipe, and FIG. 8 is a block diagram of parts.
In the conventional joint structure for connecting ends of four pipes to each other, for example, a pipe 1, a pipe 2, a pipe 3 and a pipe 4 are prepared and a joint member 5 is prepared as a separate member, and after each of the pipes are abutted to the joint member 5, welding W1 is performed at joined portions to join them.
That is, it is structurally difficult to directly join the ends of the four pipes to each other, and the joint member 5 is required. This joint member 5 is made by forging of a steel material, for example.
For welding to be conducted at the joined portion, beveling machining is needed on the pipes and the joint member.
The joint structure of a pipe structure is disclosed in Japanese Patent Laid-Open Publication No. 05-295800 and Japanese Patent Laid-Open Publication No. 2001-165126.
Use of a joint member was indispensable in the above-mentioned conventional structure.
Therefore, an object of the present invention is to provide a joint structure of a pipe which can directly join ends of a plurality of pipes.